Tool for grinding electrical contact points



June "12, 1923'.

N. A. ANDERSON TOOL FOR GRINDING ELECTRICAL CONTACT POINTS Fi-led Oct. 20. 1921 Patented June 12, 1923.

it s s ATE s NILS ALFRED nnnnnson, or NEw YoRm'N. Y.

TOOL FOR GRINDING ELECTRICALOONTACT POINTS.

Application filed October 20, 1921. Serial lilo/509,092.

T 0 all whom it may concern.

Be it known that I, NILs ALFRED ANDER- soN, a subject f the King of Sweden, and a resident of the city, county, and State of New York, have invented a certain new and useful Tool for Grinding Electrical Contact Points, of which the following is a specification.

In different parts of automobiles, especially the timer f the engine, there are make and break contact points usually made of the very hard metals such as platinum. If these contact points do not meet with smooth, parallel coacting faces but only touch each other in local spots there is a sparking action between the non-touching but adjacent portions of the faces of the contact points and this arcing is the source of several difiiculties in the operation of the motor. The arcing causes the points themselves to burn, thus destroying or removing part of the contact points themselves and also coating them with carbon. When this occurs the full current can not readily pass in the circuit and as a result, the ignition sparks in the cylinders of the engine are not sufliciently intense to produce rapid and complete combustion of all the fuel in the several cylinders of the engine. Heretofore, it has been customary to file ofi by hand the surfaces of the contact points but this method is unsatisfactory.

The object of the present invention is to provide a simple, inexpensive and very compact tool for holding the contact points whereby they may be filed or ground off smoothly and with parallel faces.

In the drawing forming part of this application,

Figure 1 is a longitudinal sectional view through the middle of the tool,

Figure 2 is a plan view of the tool,

Figure 3 is a section on the line, 33 of Figure 4 showing a contact arm in position ready for the grinding of its contact point.

Figure 4 is a plan view thereof, and

Figure 5 is an enlarged, fragmentary sectional view showing a contact screw in position for its contact point to be ground.

The device comprises a block or base 1 suitably adapted to hold the contact point members while the faces of the contact points are ground or filed off. This base has a channel 2 extending lengthwise thereof and inclining downwardly from the end 3 toward the end 4, or at least inclining in relation to the parallel, top surfaces of the side tracks 6 of the block.

The side tracks 6 extend from the end 3 of the block and preferably terminate at the abutment 7 formed by the raised, parallel walls 8. The block 1 has a socket 9 sunk below thesurface 10, the top of this socket inclining downwardly from the forward end toward the rear end so that it inclines in relation to the track surfaces 6. There are apertures 11,12, 13, 14, 15 extending through the block, the tops of theseapertures opening into the socket 9 and the bottoms opening at the bottom of the block 1. The top edges 16' ofthese apertures are preferably countersunk to receive the heads 20. of the contact carrying'screws 21 in aposition parallel with the track surfaces 6. Owing to the inclination of the bottom surface of the socket!) these apertures 12 to 15 are of different depths, for a purpose which will be tlon.

The upright walls 8'are spacedapart sufliciently to receive the make and break arm 22 of a timer between them and they are each provided with a slot 23 extending substantially lengthwise of the tool but inclined so that these slots Eire parallel with the resting surface 10, but inclined relatively to the track surfaces 6, the same'degr ee as the surmade apparent in the subsequent descripface 10.

In Figure 5 I have shown a screw 21 having a head 20 provided with the contact point 24 which is the member requiring refacing on the end; and this screw is one of the contact point holders usually employed in motor practice. I

WVhen the contact points are new they are of course longer whereas when they are ground or filed off they are. more or less shortened and this is provided for in the present device. Assuming that a contact point is to be faced off for the first time, then the screw 21 having this contact point thereon will be inserted through the aperture 11, which is the one nearest the shoulder 7 and which is therefore the shallowest aperture. The head of this screw will rest in the countersunk top 16 of this aperture 11 and the screw 21 will lie at right angles to the plane of the tracks 6. The nut 25 may be applied to the end of the screw 21 which projects below the block 1 for the purpose of holding the screw steady.

The contact point will pro ect a very slight eatent above the plane of the tracks 6. A flat surfaced stone, carborundum block or other abrasive or grinding instrument 26 is then moved back and forth across the surface of the contact point which projects above the plane of the tracks and this grinds ofl' the top surface of the contact point. When this surface has been ground off flush With the surfaces of the tracks 6 the grinding implement will contact with the surfaces of these tracks and the contact point will be no longer acted upon to any appreciable extent. .By this time the surface of the contact point will have been ground off smooth and at right angles to; the screw 21 and the operation will have been completed. When this same Contact point again requires to bare-surfaced its screw will be inserted into the aperture 12 and therefore the head will be slightly higher than when the screvs was inserted in the aperture 11 to allow for the decreased height of the contact point caused by the previous grinding operation. Thus, every time the contact point is re-surfaced thescrew 2l'isinserted into a different and deeperaperture to hold it higher in relation to the tracks. 6 in order that the top of the =conta'ct point maybe slightly above the plane of. the tracks when the resurfacing operation is started.

To resurface the contact point of the make and break lever 22 the latter is inserted between the upstanding walls 8 and a screw 27 is inserted through the slots 23 in the Walls 8 and through the aperture. 28 in the lever 22. which latter is the aperture which receives the pin on which this lever rocks when in use on the automobile. The free end of thelever 22 rests on the surface 10, which latter is inclined relatively to the surfaces of the tracks 6. The lever 22 is moved along the surface 10, the screw 27 moving in the slots 23, until a position is reached where the top surface of the contact point 28 on the lever projects slightly above the plane of the tracks 6: andthen the nut 29 is tightened to hold the lever 22 in this position. The resurfacing instrument is then moved across the surface of the contact point until the instrument grinds down this surface and commences to engage both track surfaces when the operation will be completed. The next time it becomes necessary to resurface this same contact point, the lever 22 willbe movedalong to rest its free end on a higher part of the surface 10 in order to bring the surface of the contact point slightly above I the plane of the track surfaces.

It will be noted that the slots 23 are inclined relatively to the tracks 6, and are parallel with the surface 10, so that the lever 22 will always lie at the same angle relatively to thetrack surfaces and the contact point will therefore always be faced off at the same angle.

The present device is very compact and may be carried in the tool kit always ready for use. It very inexpensive to manufacture.

Having described my invention, what I claim is 1. A tool for refacing contact points, comprising a base or holder having aligning tracks for guiding. a resurfacing tool, said base having a plurality of apertures adapted to receive therein a contact holding screw, and opening at different levels with respect to the base, whereby said base is adapted to hold said screw at different elevations relatively to said tracks in said several apertures, said tracks serving as a stop for the resurfacing tool when the latter has resurfaced the contact point of a member held in one of said apertures.

2. A tool for refacing contact points of lever arms, comprising a base or. holder having aligning tracks for guiding a resurfacing tool, and means for holding the contact carrying lever arm in different adjusted positions relatively to said tracks, comprising an inclined support for the free end ofthe lever arm adjacent said tracks and supporting means having a correspondingly inclined slot to receive a holding member passing through said lever arm, for the purpose of holding said arm in proper relation to said tracks.

3. A tool for refacing contact points of lever arms, comprising a base or holder having tracks for guiding a resurfacing tool, and, means for holding the contact carrying leverv arm in different adjusted positions relatively to said tracks, comprising an inclined support for the free end of the lever arm, adjacent said tracks, walls adaptedto receive the lever arm between them and. provided. with slots, arranged; parallel with said supporting surface and adapted to receive a member passing through, an aperture in said lever arm for thepurpose set forth.

4. A tool for refacing contact points, comprising a base or holder having tracks for guiding a resurfacing tool and having a depressed resting surf-ace inclined relatively to. saidtracks, saidv base having a recess depressed below said: resting surface and, having a plurality of screw receiving. apertures terminatingat different elevations in said recess. for, the purpose set forth, spacecLwalls adapted; to receive a lever arm. between them and having. slots for the purpose set forth, extending parallel with said resting surface.

Signed; at the city, county and State of New York, this 13th day of October, 1921-.

NILS' ANDERSON. 

